Energy balance issue ChtMultiregionFoam- wallheatflux
 

Hello All

I am using chtMultiregionSimpleFoam to simulate heat exchange between two co-current streams in a heat exchanger. I used the wallheatflux to carry out the energy balance of the converged solution. Everything adds up right except that the energy balance is off by a value of 1.2 watt and coincidentally, i observe that the wallheatflux on the inlet shows the same value. from my understanding the wallheatflux should never be evaluated at a flow patch. and flow is converged to expectation.

Please help me understand this observation.

Also is it ok to use wallheatflux function object on the coupled wall faces?